Background and Aims: The thyroid gland is characterized by numerous and variable sized follicles that are filled with colloid which are lined by a single layer cell called follicular cell. Thyroid hormones and the colloid are synthesized by these follicular cells. Disorders of thyroid function are more common in females e.g. hypothyroidism, hyperthyroidism, Graves disease and simple goitre. In India, goitre and cretinism were found to be in significant extent in the Himalayan goitre belt. The mean annual incidence rate of autoimmune hypothyroidism is up to 4/1000 women and 1/1000 men. Subclinical hypothyroidism is found in 6% - 8% of women (10% over the age of 60 years) and 3% in men. Now a days, thyroid related pathology and infertility among females are growing at an alarming rate. These pathological conditions can only be understood on the basis of thorough knowledge of thyroid structure. Considering the above mentioned factors in mind the present study on measurement of follicular diameter of female thyroid in different stages of life in female was conducted in the following groups namely “Prepubertal”, “Reproductive” and “Postmenopausal”. Materials and Methods: The study was focused on measurement of follicular diameter of female thyroid. The study was conducted in the Department of Anatomy, Gauhati Medical College, Guwahati. The specimens were divided in three age groups (0 to 10 years, more than 10 years to less than 51 years and 51 years and above).The collected specimens were cut into pieces of approximately three mm to five mm thickness and then they were subjected to routine processing. The stained sections were examined thoroughly under light microscope using both low and high power magnification. Results: In present study the average follicular diameter of thyroid follicles are 68.24 ± 10.58µ in “Prepubertal” group, 192.49 ± 7.34µ in “Reproductive” group and 116.31 ± 7.30µ in “Postmenopausal” group respectively. Conclusion: The follicular diameter of thyroid gland increases with a high significance (p<0.01.) from “Prepubertal” group to “Reproductive” group and decreases with a high significance (p<0.01) from “Reproductive” group to “Postmenopausal” group. Knowledge of normal values might be helpful in different disease condition of the thyroid gland in female.

Keywords: Thyroid; Average Follicular Diameter.